1. Field of the Invention
The present invention relates to a current sensor capable of measuring, in a non-contact manner, a current to be measured, and a manufacturing method for the current sensor.
2. Description of the Related Art
In fields such as electric vehicles and solar batteries, there have been used current sensors each of which is able to measure a current value in a non-contact manner, based on an induction magnetic field generated by a current to be measured. This current sensor includes magnetoelectric conversion elements used for detecting the induction magnetic field generated by the current to be measured, and calculates the current value of the current to be measured, based on a magnetic field strength detected by the magnetoelectric conversion elements. As the magnetoelectric conversion elements, for example, Hall elements each of which converts a magnetic field strength into an electric signal using the Hall effect, magnetoresistance effect elements each of which utilizes a change in an electrical resistance value due to a magnetic field, and so forth have been used.
In general, the magnetoelectric conversion elements used for a current sensor each have an individual characteristic variation. Therefore, in order to obtain sufficiently high current measurement accuracy, the adjustment of gain (sensitivity) and the adjustment of an offset (the deviation of a sensor output from a reference value when the current to be measured is 0 A), performed for each current sensor, are important. For example, in Japanese Unexamined Patent Application Publication No. 2006-3209, there has been proposed a current sensor enabling the temperature change of an offset to be reduced, using temperature-sensitive elements whose resistance values fluctuate in response to temperature.
The current sensor described in Japanese Unexamined Patent Application Publication No. 2006-3209 achieves high current measurement accuracy by adjusting an offset using the temperature-sensitive elements. However, in this configuration, it is necessary to actually measure a temperature characteristic while changing a condition for sensing of the current sensor at the time of adjusting the offset. Therefore, there is a problem that an adjustment process becomes complicated. In addition, in this current sensor, the temperature-sensitive elements are essential to adjust the temperature change of the offset.
The present invention is made in view of such a point, and provides a current sensor capable of achieving high current measurement accuracy by simple adjustment, and a manufacturing method for the current sensor.